My personal opinion is that trackable items simply cost too much. TB tags are what? $4 each? Coins are 2-3x that. I like the wooden nickel idea. About 50 cents to a dollar each and can be customized. If the trackable item was a low value item they probably wouldn't be as attractive to steal and it wouldn't be as much a disappointment to the owner when they went missing.
DaveA,
Where do you get those? Are they trackable?